There has been a demand in recent years for downsizing of LSI devices due to the increasing popularity of small electronic devices such as digital cameras, integrated VTRs, mobile telephones, or the like. A conventional chip-mounting package can protect a semiconductor bare chip for an LSI or the like, or facilitates testing. New packages have been applied such as CSP (chip size package) or BGA (ball grid array) in which a chip size is reduced to that of a bare chip while retaining the characteristics of the above convention chip-mounting packages.
A chip carrier without a lead such as a CSP or BGA is a relatively small package that includes a plurality of input/output connections between a chip and the corresponding substrate. A chip carrier without a lead is generally a package that includes a single-layer ceramic such as alumina. The ceramic forms a chip carrier, that is to say, a base, and the chip is mounted onto that base. The package with a chip mounted thereon is then mounted on a larger printed circuit board (PCB), or the like. More specifically, a contact pad that exhibits a mirror image relationship with the contact pad of the package is formed on a PCB. After aligning both components, the chip is electrically and mechanically connected and then surface-mounted with the PCB by reflow soldering, or the like. Normally, soldering paste or solder bump is used when the package is connected to the PCB by solder. A sealing resin (underfill material) such as an epoxy is generally injected into the gap created by the solder bump between the package substrate and the PCB substrate.
When the chip is mounted on a package or PCB, the surface area must be reduced. A flip-chip bonding method is an example of a method of reducing surface area. This method orients a connection pad on an upper surface of the chip towards a lower surface, and uses the solder bump to connect the pad onto the facing package or PCB. An underfill material is also injected when using this method since a gap is formed as a result of the solder bump between the chip substrate surface and a chip carrier substrate, or between a chip substrate surface and a PCB substrate. The underfill material does not only plug the space or gap in the connection portion, but also has the function of sealing the electrical connection points and protecting the points from a periphery, and adhering the package substrate and the PCB substrate. In addition, the material has the function of preventing the application of an excessive force on the solder bump connection portion that is a small mechanical junction point.
The filling method for the underfill material includes two methods including a capillary flow method that uses capillary action to fill from the chip peripheral edge, and a compression flow method that drops an underfill material in advance onto a position to be filled, and then mounts a substrate such as a chip or a package thereon. Recently, the capillary flow method is most commonly applied. In this method, since it may be the case that excessive underfill material may flow out from the outer periphery of a substrate such as a chip, package, or the like, testing is performed in relation to the type or amount of underfill material, or for strict management of the processing steps.
Normally, the underfill material is often an epoxy resin that approximates the coefficient of linear expansion of the solder. In this manner, durability in relation to temperature fatigue can be improved. Flow characteristics can be adjusted by including an inactive filling material. An anhydride curing agent can also be included for the object of improving heat cycle resistance characteristics, or the like.
However when using a solid curing agent such as a conventional dicyandiamide, or the like, there is the problem that the epoxy resin and the curing agent become separated. When using an epoxy resin that includes a known anhydride curing agent, the problem arises that bonding, durability, and heat cycle resistance are not achieved to a satisfactory level. Since a long period of at least one hour is required when using an epoxy resin, the problem arises that productivity is adversely affected.
A silicone resin is a known example of a highly durable resin having heat resistance characteristics. It is known that silicone resins include various curing types such as a heat-curing type, a moisture-curing type, and a photo-curing type. An addition-reaction silicone resin that employs an addition reaction between an alkenyl group and silicon atom-bonded hydrogen atom (hereafter referred to as a “hydrosilyl group”) exhibits excellent curing characteristics, and does not produce reaction by-products. Therefore suitable applications include protective materials for electric and electronic components such as integrated circuits or the like, sealing materials, underfill materials for circuit boards, glob top materials, dam filling materials, sealing for electronic modules, conformal coating, bonding materials, photosemiconductor sealing materials, component die-bonding materials, or the like (Patent Literature 2-9).    [Patent Document 1] Japanese Patent No. 3897303    [Patent Document 2] Japanese Patent No. 2691823    [Patent Document 3] Japanese Patent No. 4015722    [Patent Document 4] Japanese Unexamined Patent    Application (Translation of PCT Application), Publication No. 2004-519544    [Patent Document 5] Japanese Unexamined Patent Application, Publication No. 2008-45088    [Patent Document 6] Japanese Unexamined Patent Application, Publication No. 2003-313440    [Patent Document 7] Japanese Unexamined Patent Application, Publication No. 2003-327833    [Patent Document 8] Japanese Unexamined Patent Application, Publication No. 2001-81398    [Patent Document 9] Japanese Unexamined Patent Application, Publication No. 2007-131750